Process of treating hides and skins.



UNITED STATES PATENT OFFICE.

WILLIAM M. NORRIS, OF PRINCETON, NEW JERSEY.

PROCESS OF TREATING HIDES AND SKINS.

Patented Jan. 8, 1907.

Application filed November 16, 1905. Serial No. 287,670-

To all whom it may concern.-

Be it known that I, WILLIAM M. NoRRIs, a citizen of the United States, residing at Princeton, in the county of Mercer, State of New J ersey, have invented a new and useful Process of Treating Hides or Skins, of which the following is a specification.

My invention is applicable to the treatment of hides or skins of all descriptions; but as it is more particularly designed for small skins em loyed in the manufacutre of light leather will hereinafter use the word skin to indicate the same.

The object of my invention is to so conduct the process of preparing skins for tanning after the same have been unhaired that the skin itself, which consists, mainly, of gelatinous fibers or, chemically speaking, collogenous fibers, is thoroughly protected from injury during the process of removing the lime and preparing the stock for tanning, and

the loss of said gelatinous fibers during said process is prevented; also, to eliminate entirely from the present process of beamhouse work such materials as dog, chicken, and pigeon manure. The use of these offensive, fermentative, and putrefactive agents, which always destroy and dissolve gelatinous matter from the skins and frequently injures the grain, constitute a serious nuisance and loss to all manufacturers who are obliged to use them.

In carrying out my process I first soak the stock and lime and unhair the same in the usual manner. The lime should be well "sharpened" with red arsenic, taking one pound and a half of the latter to each bushel of the former and one hundred gallons of water, and this process so conducted that all natural oily matters in the stock are removed and the skins well worked out and free from hair. After a thorough washing with water at a normal temperature Fahrenheit) I place the skins in a solution that will so act upon the stock that it will be protected from any loss of gelatinous matter by any subsequent treatments to which it is subjected. For a pack of skins weighing six hundred pounds in the hair I take thirty pounds of hyposulfite of soda dissolved in about four hundred gallons of water in a reel and place the stock therein. The paddles are allowed to revolve for five or ten minutes, and the skins then remain in the solution for twenty-four hours. I now subject the stock to a solution which will remove the lime and other chemicals to which it has been subjected,which will cause it to fall and become'soft and flaccid For this purpose I use hydrochloric acid, salt, and water. For, say, six hundred pounds of skins I take about twenty pounds of hydrochloric acid, sixty pounds of salt (chlorid of sodium NaOl) and a suitable amount of watersay fifty gallons. This operation is conducted in a drum for about one hour. The amount of acid used depends upon the amount of alkaline matter in the stock requiring to be neutralized. Skins should be examined by cutting through the thickest part of the necks and testing with phenolphtalein to determine that all alkalies have been neutralized or killed. At the same time only the slightest excess of acid possible should be employed.

On some classes of stocksay skins that are thick and heavyI find it desirable to use some saccharine mattersay five pounds of sugar or glucose. This is added to the above composition of hydrochloric acid, salt, and water. These substances will remove lime from the skins and make it unnecessary to use as much acid as would be otherwise required. The stock after being treated as above is now slated to remove all fine hairs and other non-tannable matter. If washing the skins while in this state should be deemed necessary or desirable, some saltsay five poundsshould be added to one hundred gallons of water with which such stock is washed in order to prevent any swelling or plumping. I now subject the skins to a slight tawing treatment. For a pack of six hundred pounds of stock I take fifteen pounds of sulfate of alumina, AJ (SO )3, thirty pounds of salt, and a suitable amount of watersay fifty gallons. This operation is conducted in a drum and takes about half an hour. The skins are now ready for tanning. Such stock treated as above is well prepared and especially adapted to the chrome process of tanning as practiced to-day and should be at once subjected to the first bath or step of said process, composed of five per cent of the weight of the skins of bichromate of potash, two and one-half per cent. hydrochloric acid, and a suitable amount of water and then subjected to the various subsequent steps of the well-known chrome process The hydrochloric acid referred to is the muriatic acid of commerce and should stand 21 on a Baum hydrometer. The hyposulfite ofsoda is the article known as such in the trade, (sodium thiosulfate, N a S O The temperature of all the solutions referred to above should be about 60 Fahrenheit.

Having thus described my invention, what I claim as new, and desire to secure by Letters Patent, is-

-1. The within-described improvement in treating hides and skins, which consists in depilitating them in lime and arsenic and then subjecting them to the direct action of" hyposulfite of soda and then to acid. r

2. The Within-described improvement in treating skins which consists in depilitating them inlime and arsenic, subjecting them to I 5 the direct action of a solution of hyposulfite of soda to set the gelatinous fibers of the P. A. V. VAN DoRN, JOHN H. OoNEY. 

